Dex-Cool, in GM 3.8

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monte

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Some recent posts have me a little worried about the coolant in my 3.8L GM V6. Anyone have some specific info. on the problems and what to look for. And how to remedy it? Should I flush the Dex-cool and put in something else?
BTW. The car runs well. Does not overheat, and has about 30K miles.
Thanks
 
What car, what year, and what engine? Is it a 3800 Series II/III, or a newer 3.8?

The 3800's are known to have leaky lower intake manifold gaskets that result from the Dex-Cool eating away at the gaskets as it gets acidic over time.

I'd flush it out and replace it with Prestone All-Makes and distilled water.

My $0.02.
 
Originally Posted By: monte
Should I flush the Dex-cool and put in something else? BTW. The car runs well. Does not overheat, and has about 30K miles.
Thanks

My advice is to get it out of there.
Its way beyond the warranty period, any problems now are going to come out of your pocket.

Don't believe the myths about replacing Dex-cool, it can be done successfully, just be sure to flush the system well.
I open the drain plug, remove the radiator cap, pull off a bypass hose, and back flush a few times with a garden hose, (heater control on high), until the water runs clear.
 
The intake gaskets leak because there is a hard plastic skeleton that holds the rubber seals in place. The plastic always cracks, causing the rubber seal to deform, and then leak coolant.

I'd just flush the Dexcool now, and then replace it every 2-3 years afterwards.
 
Originally Posted By: artificialist
I'd just flush the Dexcool now, and then replace it every 2-3 years afterwards.

Right, then cross your fingers there are no minor malfunctions of the cooling system in meantime that cause the Dex-cool to turn into red muck.

Sorry, if I sound slightly bitter but a Dex-cool fiasco cost us $750 on a '99 Monte with the 3.1L engine at under 60,000 miles.
I'd like to spare others the same expense and inconvienience.
 
It's sounding like I should change the stuff out. Should I put in the conventional green stuff or is there something else to use? Is there anyway to know if there has been a leak through any gaskets? Would the coolant in the overflow tell the story?
Thanks for the advice
 
Originally Posted By: monte
It's sounding like I should change the stuff out. Should I put in the conventional green stuff or is there something else to use? Is there anyway to know if there has been a leak through any gaskets? Would the coolant in the overflow tell the story?

Monitor the coolant recovery tank on regular basis, any mysterious loss of coolant is a bad sign and must be investigated.
Worse case scenario; coolant leaks into engine and contaminates the motor oil which can quickly cause bearing damage if not caught in time.

Conventional green coolant is fine, but should be flushed every 30,000 miles or so.
 
Lot of alarmest...
At any rate. If you want to change to the green stuff, get all the old out or it will gel up; however; it is not necessary.

The gasket problem is an issue, but not as many cars have it as you would believe.

In 2001 the 3800 got updated gaskets and intake which eliminates the problem. Direct bolt on for the older ones with the problem

I had a 98 Bonneville that I put 210,000 miles on I changed the coolant every 40,000 miles, which was the key to not having any problem.

The 3.1 was totally different.

Cars I have owned with Dex Cool
98 Bonneville 210,000 miles
2001 GTP 230,000 miles
04 Silverado 72,000 miles
98 Z28 120,000 miles
2001 Z28 52,000 miles
My current Trans Am and Equinox.

Just don't get scared, and don't be stupid about it. If you are really worried get the updated intake and gasket. Spend a saturday swapping it out and move on.
Or do a flush every 30,000 to 50,000 miles like you will end up doing with green stuff anyway.
 
Originally Posted By: ls1mike
Lot of alarmest...
At any rate. If you want to change to the green stuff, get all the old out or it will gel up; however; it is not necessary.

The gasket problem is an issue, but not as many cars have it as you would believe.

In 2001 the 3800 got updated gaskets and intake which eliminates the problem. Direct bolt on for the older ones with the problem

I had a 98 Bonneville that I put 210,000 miles on I changed the coolant every 40,000 miles, which was the key to not having any problem.

The 3.1 was totally different.

Cars I have owned with Dex Cool
98 Bonneville 210,000 miles
2001 GTP 230,000 miles
04 Silverado 72,000 miles
98 Z28 120,000 miles
2001 Z28 52,000 miles
My current Trans Am and Equinox.

Just don't get scared, and don't be stupid about it. If you are really worried get the updated intake and gasket. Spend a saturday swapping it out and move on.
Or do a flush every 30,000 to 50,000 miles like you will end up doing with green stuff anyway.


Wrong. The gasket problem happens on EVERY SINGLE 3.1, 3.4, 3.8, 4.3, 5.0, 5.7, and 7.4 motor. Every single UOA posted here with these engines shows coolant in the oil if it has the factory gaskets.

The updated intake manifold came out with the Series III 3.8L in 2004, but people are still reporting gasket failures until about 2005.

So, to the original poster - if you aren't mechanically inclined, I'd purchase the Series III intake manifold and a Fel Pro problem solver intake manifold gasket set and just get it done. It will leak, GARUNTEED. Once it's fixed with these parts, the engine will be one of the most rock solid and reliable you could get. I'd have no issue continuing to use Dexcool, but I would flush and fill on a regular basis - say ever 30,000 to 50,000 miles.

One way to see if you actually have an internal leak is to get a UOA.
 
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We were only talking about the 3800 and 3.1 here.
I am aware of the fact that the problem has been in other.
There is a change to the manifold in 01 on how the stove pipe for th EGR enters it in 01, 2004 got the completey diffrent intake.
 
Originally Posted By: Drew99GT
I'd have no issue continuing to use Dexcool, but I would flush and fill on a regular basis - say ever 30,000 to 50,000 miles.

What is the point of using Dex-cool if it must be flushed every 30-50,000 miles?

Might as well use conventional green coolant and have peace of mind knowing it won't turn into sludge because the radiator cap or something else malfunctioned.
 
True, you make a valid arugument, but if you change the cap at flushes like you should I do believe it is better for the particular type of raditor they are running.
At the LSX boards where everything uses Dex cool it has just worked better with the Type of Radiators F-bodies, Corvettes and LSx trucks have been using. I can't speak for the other motors not sure what their radiators are made of.

I can't off hand think of a LSX based car that has had a sludge problem until they swapped to the green stuff and were not careful to get all the Dex Cool out.
 
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I think for the 3.1 & 3.4 motors the Fel Pro problem solver gasket is the way to go but for the 3.8L motors GM makes a metal framed gasket that is problem the best way to go. They never offered a metal framed one for the 3.1/3.4 motors so Fel Pro is the best bet for those.

As for the manifold update the following link is a good manifold to replace yours with. It also includes the updated EGR tube. This prevents erosion of the area around the tube.
http://www.autopn.com/store/pc/viewPrd.asp?idproduct=229679

ls1mike, perhaps not every engine leaks but everyone I've had or a family member has had or anyone I know that has one of the listed motors has had a leaker. Must be pretty common. My mechanic does them all the time he says. It pays to be very cautious if you ask me.

Monte, your car could already be leaking. My UOA hardly showed anything conclusive other than slightly elevated potassium and sodium levels but still pretty low numbers. You could see oily goop under the radiator cap of my '01 Grand Prix. I just had mine redone with the GM metal framed gaskets (they still have plastic ones so make sure you get the right ones) and the new intake listed above just to be safe.

As was already mentioned, keep a close eye on your over flow tank for a drop in coolant. Always check it after it sits for the night so it will give you a consistent reading. Sometimes you will see creamy junk collecting under your oil fill cap as well if there is coolant in the oil.

Good luck. In the grand scheme of things it really isn't a ton of money. At least you don't have a timing belt to replace which could cost just as much and be required more often. It is a shame GM let this happen and wasn't willing to make it right with its customers when problems arose. I'm sure they lost a lot of long term customers because of it.
 
I already submitted 3 claims on the class action suit.
11.gif


What a shame. These GM motors, especially the 3800, are as rock solid as they come................save for this stupid intake manifold and gasket problem. GM shot themselves in the arse bigtime on this deal.
 
Well the current 3.4 shares nothing intake, valve train and radiator wise (no cap, just pressurised overflow) with the previous one. The 3.6 and the LSX motors don't have the problem either.
 
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